Agroforestry systems and soil surface management of a tropical alfisol: I: Soil moisture and crop yields

Abstract

Field experiments were conducted on a tropical Alfisol at Ibadan, Nigeria, to evaluate the effects on soil moisture and crop yields of three agroforestry systems. Effects of agroforestry treatments involving two perennial shrubs (Leucaena leucocephala and Gliricidia sepium), each at 2-m and 4-m row spacings, were compared with no-till and plow-till systems of seedbed preparation. Measurements were made for soil properties, runoff and erosion, nutrient losses in runoff, and crop growth and yield for a uniform maize (Zea mays) and cowpea (Vigna unguiculata) rotation. All of the six plots, each measuring 70 x 10m, were established on a natural slope of about 7%. Alterations in soil properties and effects on crop growth were evaluated for six consecutive years from 1982 through 1987.Seed germination and seedling establishment of Leucaena hedgerows were satisfactory while establishment of Gliricidia from stem cuttings was unsatisfactory. Maize germination and crop stand were normal while that of cowpea were suppressed by both Leucaena and Gliricidia. Maize growth and yield were suppressed only in the vicinity of hedgerows. Maize grain yield in agroforestry systems averaged about 10 percent lower than that of the control. In contrast with maize, agroforestry systems drastically suppressed cowpea grain yield. The average cowpea yield in agroforestry systems was 30 to 50% of the control. Regardless of the mangement system, grain yields declined over time at the rate of 340 and 96 kg ha-~ yr -~ for maize and cowpea, respectively.Hedgerows of Leucaena and Gliricidia acted as windbreaks, Consequently, soil moisture content in the top 0-5 cm layer in agroforestry systems was generally higher than that in the control during both wet and dry seasons.

Making Soil and Water Conservation Sustainable: From Coercion and Control to Partnerships and Participation

“…Alley cropping, an agroforestry system comprising rows of nitrogen-®xing trees or bushes separated by rows of cereals, has long been the focus of research (Kang, et al, 1984;Attah-Krah and Francis, 1987;Lal, 1989). Many productive and sustainable systems, needing few or no external inputs, have been developed.…”

Biophysical interactions in tropical agroforestry systems

“…One of the sites with yield increases was a highland area in Rwanda with bimodal rainfall, where typical crop yields were very low (Balasubramanian and Sekayange, 1991); at the other site, soil and hedgerow management were very good (Bunderson, 1992). In subhumid environments (rainfall between 1000 Akyeampong and Hitimana, 1996;Balasubramanian and Sekayange, 1991;Bundersen, 1992;Chiyenda and Materechera, 1989;Duguma et al, 1994;Evensen et al, 1995;Fernandes et al, 1993;Hauser and Kang, 1993;ICRAF, 1995;Kang, 1993;Kang et al, unpublished;Kass et al, 1995;Lal, 1989a;Matthews et al, 1992a, b;Mathuva et al, 1997;Mittal and Singh, 1989;Mugendi et al, 1997;Mureithi et al,1994;Rao et al, 1991a;Rosecrance et al, 1992;Schroth et al, 1995b;…”

“…Boundary plantings of eucalyptus have been widely reported to affect adjacent crops due to allelopathy (Willis, 1991). Lal (1989a) reported poor germination and seedling establishment of cowpea in leucaena and gliricidia hedgerow systems in Ibadan, Nigeria, which often resulted in lower yields of cowpea under HI than in sole crop control. Interestingly, maize germination was not affected by the hedgerows.…”

Better land husbandry in Honduras: towards the new paradigm in conserving soil, water and productivity

“…Reasons for non-adoption and adaptation of SC technologies * Farmers feel that they are unlikely to reap expected benefits because of a lack of secure access to land (Bunch, 1982: 45;Sanders, 1988;Comia et al, 1994;Wachter, 1994). * Labour costs involved in establishment and maintenance of technologies are too high, especially if farmers periodically work off-farm (De Janvry et al, 1989;Douglas, 1993;Zimmerer, 1993;Critchley et al, 1994;Stocking, 1995;Garrity et al, 1997;Lal, 1989). * Technologies do not reliably reduce soil loss and, even if they do, the reduction does not, immediately, raise yields (Pretty, 1995: 51).…”